Cooling system for fuel cell

ABSTRACT

A cooling system for fuel cell capable of smoothly adjusting the temperature of cooling liquid and supplying a lot of cooling liquid with low temperature as far as it is possible into an ion exchanger, furthermore, driving a fuel cell under the favorite condition could be provided by comprising of the heat exchanger  3  to chill first cooling liquid discharged from a fuel cell FC, the heat regulator  13  to adjust the temperature of first cooling liquid supplying into a fuel cell FC after mixing first cooling liquid chilled in the heat exchanger  3  with first cooling liquid bypassed the heat exchanger  3,  the ion exchanger  14  using the ion exchange resin to remove ion in first cooling liquid, the supply controller to supply first cooling liquid bypassed the heat exchanger  3  into the ion exchanger  14  when the temperature of first cooling liquid exceeded the adjustable range of temperature by the heat regulator  13  and to supply first cooling liquid chilled in the heat exchanger  3  into the ion exchanger when the temperature of first cooling liquid is within the adjustable range of temperature by the heat regulator  13.

FIELD OF THE INVENTION

[0001] The present invention relates to a cooling system for a fuel cell to cool a fuel cell, more particularly to a cooling system equipped with an ion exchanger to remove ion in cooling liquid.

PRIOR ART

[0002] Recently, a fuel cell (polymer electrode membrane type fuel cell) has drawn attention as a power source of an electric vehicle etc., because of its cleanness and excellent energy efficiency. This fuel cell is one species of generator to electrochemically generate when fuel gas (hydrogen) and oxidant gas (air) are supplied. A temperature of a fuel cell is risen by being heated when generating. In the mean time, a fuel cell has an appropriate temperature range for driving. Due to this, a polymer electrode membrane type fuel cell drives a fuel cell in the appropriate temperature (approximately 85° C.) by supplying cooling liquid of a predetermined temperature (approximately 70° C.).

[0003] Furthermore, when an ion exchange resin is thermally decomposed, the substance yielded in thermal decomposition deteriorates conductivity. On the other hand, a controlling temperature of a fuel cell, namely, a controlling temperature of cooling liquid supplying into a fuel cell is higher (for example 70±2° C.) than the temperature (a heat-proof temperature of an ion exchange resin) which the ion exchange resin can be used for a long time under the favorite condition, communicating this cooling liquid with an ion exchanger by this temperature causes an ion exchange resin retrogression. For this reason, a cooling liquid of low temperature is supplied into ion exchanger, what is more, more than predetermined amount of cooling liquid to control conductivity is needed to continue flowing in the heat exchanger.

[0004] Conventional cooling system for a fuel cell 50 is shown in FIG. 4. This cooling system for fuel cell 50 has the bypass line 51A to bypassed the first circulating pump 53, the heat exchanger 58 and the heat exchanger 58, and in addition, the heat regulator 54 (thermostat valve) to adjust the temperature of first cooling liquid by mixing cold first cooling liquid (approximately 60° C.) circulated through the heat exchanger 58 with warm first cooling liquid (approximately 80° C.) circulated through the bypass line 51A on the first cooling system 51 (cooling system) circulating and supplying first cooling liquid (cooling liquid) into a fuel cell FC. And then first cooling liquid (cooling liquid) adjusted the temperature to 70±2° C. by the heat regulator 54 is supplied into a fuel cell FC.

[0005] Hereupon, this cooling system for fuel cell 50 removes ion by the ion exchanger 55 by picking up some of cold first cooling liquid circulated through the heat exchanger 58 and then put them back into an inhalant side of a circulating pump 53 for maintaining low conductivity of first cooling liquid.

[0006] Besides, a code 15B is the supply line to supply first cooling liquid circulated through the heat exchanger 58 into the ion exchanger 55, and a code 51C is the return line to return first cooling liquid removed ion by the ion exchanger 55 to the first cooling system 51. Furthermore, a code 52 is the second cooling system to chill the first cooling system 51, and a code 56 is the second circulating pump, a code 57 is a radiator to chill the second cooling system 52.

[0007] According to this cooling system for fuel cell 50, for example, cold first cooling liquid after circulated through the heat exchanger 58 can be always circulated into the ion exchanger 55 compared with extracting first cooling liquid (mixed with warm first cooling liquid) of which temperature was adjusted from a lower portion of the heat regulator 54.

SUMMARY OF THE INVENTION

[0008] However, extracting first cooling liquid (cooling liquid) in front of the heat regulator 54 causes the following problem. Specifically, cold first cooling liquid supplying into the heat regulator 54 will be insufficient when the temperature of the whole first cooling system 51 is increased due to an increase of a load of fuel cell FC (and/or a capacity degradation of the heat exchanger 58). For this reason, temperature-adjustment by the heat regulator 54 exceeded the limited value, consequently, this causes the problem so that first cooling liquid appropriately adjusted in temperature can not be supplied into a fuel cell FC as the cooling system for a fuel cell 50. Specially, when a fuel cell FC is used under the condition of drastically load fluctuation, for example, when a fuel cell FC is equipped with electrical vehicles, it is assumed that a lot of related problem is occurred. Besides, returning the first cooling liquid circulated through the ion exchanger 55 to the lower portion of the heat regulator 54 may be available. However, it is inappropriate for temperature management to mix first cooling liquid adjusted by the heat regulator 54 with non-adjusted cooling liquid.

[0009] Thereupon, the primary object of the present invention is to provide a cooling system for a fuel cell which is capable of smoothly adjusting the temperature of cooling liquid and supplying a lot of cooling liquid with low temperature as far as it is possible into an ion exchanger, furthermore, driving a fuel cell under the favorite condition.

[0010] A cooling system for fuel cell described in claim 1 of the present invention attained said object is equipped with a heat exchanger to chill cooling liquid discharged from a fuel cell, a temperature-adjuster to adjust the temperature of cooling liquid supplying into said fuel cell after mixing cooling liquid chilled in said heat exchanger with cooling liquid bypassed said heat exchanger, an ion exchanger using the ion exchange resin to remove ion in said cooling liquid, a supply controller to supply cooling liquid bypassed said heat exchanger into said ion exchanger when the temperature of cooling liquid is exceeded the adjustable range of temperature by said temperature-adjuster and to supply cooling liquid chilled in said heat exchanger into said ion exchanger when the temperature of cooling liquid is within the adjustable range of temperature by said temperature-adjuster.

[0011] In this structure, when the temperature of cooling liquid is within the adjustable range of temperature (within the controllable range) by the temperature-adjuster, the cooling liquid circulated through a heat exchanger is supplied into an ion exchanger. Accordingly, a thermal degradation of ion exchanger can be prevented. On the other hand, when the temperature of cooling liquid exceeded the adjustable range of temperature (controllable range) by the temperature-adjuster, the cooling liquid bypassed a heat exchanger is supplied into ion exchanger.

[0012] Accordingly, the temperature-adjustment is smoothly carried out without a shortage of cooling liquid circulated through a heat exchanger by the temperature-adjuster. What is more, since cooling liquid in the lower portion of the temperature-adjuster is the adjusted cooling liquid, extracting this liquid does not have an influence on the temperature-adjuster.

[0013] That is to say, when the temperature of cooling liquid is within the adjustable range of temperature by the temperature-adjuster, cold cooling liquid is supplied into an ion exchanger, and when the temperature of cooling liquid exceeded the adjustable range of temperature, cold cooling liquid is no longer supplied into an ion exchanger. Accordingly, temperature controlling of cooling liquid can be smoothly carried out, what is more, the cooling liquid (low temperature) with low temperature as far as it is possible is supplied into an ion exchanger.

[0014] Besides, the supplying controller in the embodiment of the present invention, which will be described later is comprised of two solenoid valves etc., when cooling liquid is circulated through one of two solenoid valves, the other one shutdown a circulation of cooling liquid.

[0015] Additionally, the cooling system for fuel cell described in claim 2 has a temperature detector to detect the temperature of said cooling liquid and a structure to supply cooling liquid bypassed said heat exchanger into said ion exchanger when the temperature of said cooling liquid is below the predetermined temperature and to supply cooling liquid chilled in said heat exchanger into said ion exchanger when the temperature of said cooling liquid is above the predetermined value.

[0016] According to this structure, the temperature of cooling liquid supplying into a fuel cell can be adjusted more smoothly by detecting the temperature of cooling liquid.

BRIEF DESCRIPTION OF THE DRAWINGS

[0017]FIG. 1 is a drawing to explain the structure of a cooling system for fuel cell regarding to the embodiment of the present invention.

[0018]FIG. 2 is a cross sectional view to explain the structure and actuation of the heat regulator of FIG. 1, (a) shows the situation that a main passage is communicated and a bypass passage is isolated, (b) shows the situation that a main passage is isolated and a bypass passage is communicated.

[0019]FIG. 3 is a flow chart to explain the actuation when supplying first cooling liquid into the ion exchanger of FIG. 1.

[0020]FIG. 4 is a drawing to explain the structure of conventional cooling system for fuel cell.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] Following is the detailed explanation of the embodiment of the present invention with reference to the drawings.

[0022]FIG. 1 is the drawing to explain the structure of the cooling system for fuel cell regarding to the embodiment. FIG. 2 is a cross sectional view to explain the structure and actuation of the heat regulator of FIG. 1, (a) shows the situation that a main passage is communicated and a bypass passage is isolated, (b) shows the situation that a main passage is isolated and a bypass passage is communicated.

[0023] The cooling system for fuel cell M regarding to the embodiment, as shown in FIG. 1, has a first cooling system 1 in which first cooling liquid to chill a fuel cell FC is circulating and a second cooling system 2 in which second cooling liquid to chill a first cooling system is circulating.

[0024] First cooling system

[0025] A first circulating passage 11 to circulate and supply cooling liquid into a fuel cell FC is formed in a first cooling system 1. This first circulating passage 11 is equipped with a first circulating pump 12 to circulate first cooling liquid, a heat exchanger 3 to chill a first cooling liquid system 1 (first cooling liquid) on the lower portion of a first circulating pump 12, a bypass line 11A bypassing a heat exchanger 3 on the lower portion of a first circulating pump 12, and a heat regulator 13 of the temperature-adjuster to adjust the temperature of cooling liquid by mixing cold first cooling liquid circulated through the heat exchanger 3 with warm first cooling liquid circulated through the bypass 11A.

[0026] Besides, the heat regulator 13 hereupon is a thermostat value. This heat regulator 13 has the structure shown in FIG. 2 (a) and FIG. 2 (b). That is to say, a main passage 13A and a bypass passage 13B are provided inside of the heat regulator 13 for circulating first cooling liquid.

[0027] Furthermore, the heat regulator 13 has the element 13C in which a main valve element 13Ca to communicate or isolate the stream of first cooling liquid circulating through a main passage 13A is provided on the lower portion and a bypass valve element 13Cb to isolate or communicate the stream of first cooling liquid circulating through a bypass passage 13B is provided on the upper portion.

[0028] This element 13C has internal space, together with, a diaphragm 13Cc sectioning this internal space into two, a piston 13Cd, and a plunger 13Ce connected with a piston 13Cd. Wax inflating or shrinking depend on the temperature of first cooling liquid is filled in the one side of the internal space sectioned by the diaphragm 13Cc of the element 13C, the liquid transmitting inflation or shrinkage of wax to the piston 13Cd is filled in the other side of internal space. Additionally the heat regulator 13 has a pressure spring 13D to press the element 13C downward. This heat regulator 13 is structured so that the inlet of the main passage 13A is connected with the passage (first circulating passage 11) of first cooling liquid from the heat exchanger 3 and the outlet of the main passage 13A is connected with the passage of first cooling liquid (first circulating passage 11) toward a fuel cell FC, in the mean time, the inlet of the bypass passage 13B is connected with the bypass line 11A. Besides, in the inside of the heat regulator 13, the bypass passage 13B joins with the main passage 13A at the lower portion of the element 13C (a main value element 13Ca and a bypass value element 13Cb). Consequently, the outlet of a bypass passage 13B is also the outlet of the main passage 13A.

[0029] Following is the explanation of the actuation of this heat regulator 13.

[0030] When the temperature of first cooling liquid is high, as shown in FIG. 2 (a), wax is inflated. For this reason, a plunger 13Ce is protruded from the main body of the element 13C against the pressure of a pressure spring 13D to push up the element 13C (namely, the main valve element 13Ca and a bypass valve 13 element Cb) upward. Accordingly, a main passage 13A is communicated with a main valve element 13Ca and a bypass passage 13B is isolated by a bypass valve element 13Cb. In this situation, only cold first cooling liquid from the heat exchanger 3 is supplied into a fuel cell FC of a lower portion by circulating through a heat regulator 13. (Refer to a thick block arrow in a drawing).

[0031] Besides, continuing this situation causes wax to be chilled and gradually shrunken by cold first cooling liquid from the heat exchanger 3. Consequently, the plunger 13Ce is gradually pushed into a body of the element 13C by the pressure of a pressure spring 13D. Sequentially, element 13C is gradually moved downward. In accordance with this, the stream of cold first cooling liquid from the heat exchanger 3 is gradually decreased, and in response to this, the stream of warm first cooling liquid from a bypass line 11A is gradually increased. Therefore, the temperature of first cooling liquid after circulated through the heat regulator 13 is gradually increased (the actuation of temperature adjustment when the temperature of first cooling liquid became low).

[0032] On the other hand, when the temperature of the first cooling liquid is low, as shown in FIG. 2 (b), wax is shrunken. For this reason, the plunger 13Ce is pushed into the main body of element 13C by the pressure of a pressure spring 13D to push down the element 13C (namely, a main valve element 13Ca and a bypass valve element 13Cb) downward. Accordingly, the main passage 13A is isolated by the main valve element 13Ca and the bypass passage 13B is communicated by the bypass valve element 13Cb. In this situation, only warm first cooling liquid from the bypass line 11A is supplied into a fuel cell FC of a lower portion through the heat regulator 13 (refer to black thick arrows in a drawing).

[0033] Besides, continuing this situation causes wax to be warmed and gradually expanded by warm first cooling liquid from the bypass line 11A. Then the plunger 13Ce is gradually protruded from a main body of element 13C against the pressure of a pressure spring 13D. Accordingly, the element 13C is gradually moved upward. In accordance with this, the stream of warm first cooling liquid from the bypass line 11A is gradually decreased, reversibly, the stream of cold first cooling liquid from the heat exchanger 3 is gradually increased. Accordingly, the temperature of first cooling liquid after circulated through the heat regulator 13 is gradually decreased (the actuation of temperature adjustment when the temperature of first cooling liquid became high).

[0034] In this way, the heat regulator 13 adjusts the temperature of first cooling liquid supplying into a fuel cell FC so as to be the invariable temperature range (approximately 70±2° C.) by increasing the ratio of cold first cooling liquid when the temperature of first cooling liquid circulating through inside of the heat regulator 13 became high and in an opposite case, by increasing the ratio of warm cooling liquid when the temperature of first cooling liquid circulating through inside of the heat regulator 13 became low.

[0035] By the way, the first circulating passage 11 has the ion exchanger 14 used an ion exchange resin to remove several species of ion in first cooling liquid, in addition, the first supply line 11B1 supplying ion the exchanger 14 by extracting a part of first cooling liquid from lower portion of the heat regulator 13 and upper portion of a fuel cell FC, the second supply line 11B2 supplying into the ion exchanger 14 by extracting a part of first cooling liquid from upper portion of the heat regulator 13 and lower portion of the heat exchanger 3, and the returning line 11C for returning first cooling liquid circulated through the ion exchanger 14 to inhalant side of first circulating pump 12. At the same time, the first supplying line 11B1 has the first solenoid valve SV 1 isolating or communicating with this line 11B1 and the second supplying line 11B2 has the second solenoid valve SV2 isolating or communicating with this line 11B2. Hereupon, the supply controller is comprised of the first supply line 11B1 and the second supply line 11B2, the first solenoid valve SV1 and the second solenoid valve SV2, what is more, the controller CU which will describe later.

[0036] Besides, the first cooling system 1 and equipment provided in this first cooling system 1 are comprised of the noncorrosive materials for preventing liquid junction such as stainless steel, resin material and resin lying metallic materials. Furthermore, demineralized water (mixed with engine antifreeze such as ethylene glycol in case of necessary) or heating medium oil are used for first cooling liquid. In the present invention, engine antifreeze mixed with ethylene glycol is used.

[0037] Furthermore, the first circulating passage 11 has the temperature sensor T to detect the temperature of first cooling liquid on the lower portion of the heat regulator 13 and the upper portion of a fuel cell FC.

[0038] What is more, the first circulating passage 11 has the controller CU by inputting a detecting signal of the temperature sensor T in case of (1); when the temperature of first cooling liquid is under the predetermined value (in this case, below 72° C.), the first solenoid valve SV1 is positioned in isolating area and the second solenoid valve SV2 is positioned in communicating area, in case of (2); when the temperature of first cooling liquid is above said predetermined value, the first solenoid valve SV1 is positioned in communicating area and the second solenoid valve SV2 is positioned in isolating area.

[0039] What is more, the predetermined temperature is set so as to be a maxim value (72° C.) of adjustable range of temperature in the heat generator 13, and increase cold first cooling liquid supplying into the heat generator 13 when the prescribed temperature exceeded the adjustable range of temperature in the heat regulator 13,

[0040] Second cooling system

[0041] The second circulating passage 21 is formed to circulate and supply second cooling liquid into the heat exchanger 3 to chill first cooling system 1. This second circulating passage 21 has a second circulating pump 22 to circulate second cooling liquid and a radiator 23 to chill second cooling system (second cooling liquid).

[0042] Besides, the radiator 23 is a general style to be used in vehicles, etc. Furthermore, same one as first cooling liquid can be used for second cooling liquid. In the embodiment, it is demineralized water mixed with ethylene glycol.

[0043] Fuel cell

[0044] In this connection, a fuel cell FC of the embodiment is EPM type fuel cell, and has a layer structure piled up approximately 200 single cells of which electrolytic structure (MEA) comprised of oxygen pole and hydrogen pole by pinching electrode membrane is more pinched by a separator.

[0045] Each separator has the passage of first cooling liquid to chill a fuel cell 1 for driving in appropriate temperature.

[0046] Hereupon, PEM is short for Proton Exchange Membrane, and MEA is short for Membrane Electrode Assembly.

[0047] The actuation of a cooling system for fuel cell

[0048] The actuation of aforementioned cooling system for fuel cell is described. FIG. 3 is the flow chart to explain the actuation when supplying first cooling liquid into the ion exchanger.

[0049] When a cooling system for fuel cell M is started, the first circulating pump 12 of a first cooling system 1 and the second circulating pump 22 of a second cooling system 2 is started.

[0050] Then the first cooling liquid is begin to circulate through the first cooling system 1 and the second cooling liquid is begin to circulate through the second cooling system 2 respectively. The heat generated in a fuel cell FC is transmitted in the sequence of first cooling liquid, the heat exchanger 3, second cooling liquid and the radiator 23 to radiate outside.

[0051] In the first cooling system 1, the heat regulator 13 properly mixes cold first cooling liquid circulated through the heat exchanger 3 with worm first cooling liquid bypassed the heat exchanger 3 and adjusts the temperature to invariable range (hereupon 70±2° C.) to supply them into a fuel cell FC.

[0052] What is more, in the first cooling system 1, a part of first cooling liquid is extracted to supply into the ion exchanger 14 through either the first supply line 11B1 or the second supply line 11B2. Besides, first cooling liquid removed ion in the ion exchanger 14 is returned to the inhalant side of the first circulating pump 12 through the returning line 11C.

[0053] Hereupon, the actuation (the actuation of a controller CU) when supplying first cooling liquid into the exchanger 14 is described. (Refer to a flow chart in FIG. 3).

[0054] As shown in FIG. 3, the desired temperature of first cooling liquid is read in the step S1. The desired temperature of this step is the high limit value of an adjustable range of temperature of the heat regulator 13, namely, that is said prescribed temperature (72° C.). Secondly, the temperature of first cooling liquid detected by the temperature sensor T is read in the step S2. And then making a decision whether the temperature of first cooling liquid is under the desired value or not is carried out in the step S3.

[0055] When the temperature of first cooling liquid is below the desired vale (YES) such as when starting or normally driving a fuel cell FC, it can be decided that the temperature of first cooling liquid dose not exceed the adjustable range of temperature of the heat regulator 13, therefore, the first solenoid valve SV1 is positioned in an isolating area, at the same time, the second solenoid valve SV2 is positioned in a communicating area in the step 4.

[0056] This allows cold first cooling liquid circulated through the heat exchanger 3 (in front of the heat regulator 13) to be supplied into the ion exchanger 14 through the second supply line 11B2. Therefore, the ion exchanger 14 can be used under the favorite condition.

[0057] Besides, when the fuel cell FC is normally driven under the normal condition, a lot of cold first cooling liquid circulated through the heat exchanger 3 is supplied into the ion exchanger 14 in the step S4.

[0058] In this connection, when warming up a fuel cell FC light after starting, the heat regulator 13 is in the situation of FIG. 2 (b), first cooling liquid circulated through the bypass line 11A is supplied into a fuel cell FC, consequently warming up a fuel cell FC can be rapidly carried out.

[0059] On the other hand, when the temperature of first cooling liquid is higher than the desired value such as when a calorific value of a fuel cell FC is increased (NO), it can be decided that the temperature of first cooling liquid exceeded the adjustable range of temperature of the heat regulator 13, therefore, the first solenoid valve SV1 is positioned in a communicating area, at the same time, the second solenoid valve SV2 is positioned in an isolating area in the step 5. Due to this, First cooling liquid which was adjusted in the temperature by circulating through the heat regulator 13 is supplied into the ion exchanger 14 through the first supply line 11B1.

[0060] Explaining this respect in more detail, when the temperature of first cooling liquid is higher than the desired value (when exceeding the adjustable range of temperature of the heat regulator 13), it is the situation that cold first cooling liquid circulated through the heat exchanger 3 is insufficient in the heat regulator 13. That is to say, in spite of that the heat regulator 13, as indicating in FIG. 2 (a), is isolating the bypass passage 13B and communicating with the main passage 13A, it is the situation that the temperature of the first cooling liquid supplying into a fuel cell FC is higher than the desired value due to a shortage of cold first cooling liquid.

[0061] Hereupon, the controlling means CU is needed to increase the amount of cold first cooling liquid supplying into the heat regulator 13 and to position the first solenoid valve SV1 in the communicating area, at the same time, to position the second solenoid valve SV2 in the isolating area.

[0062] This prevents cold first cooling liquid from being extracted in front of the heat regulator 13, therefore, the heat regulator 13 can restrict the temperature of first cooling liquid supplying into a fuel cell FC to bellow the desired value by using the increased first cooling liquid.

[0063] By the way, this situation causes first cooling liquid after adjusting temperature by the heat regulator 13 to be supplied into the ion exchanger 14, however, the situation such as this is considerably short for a total amount of driving time of a fuel cell FC and this has little influence on the life span of the ion exchange resin of the ion exchanger 14. Rather than this, prioritizing an adjustment of the temperature of first cooling liquid and supplying first cooling liquid of appropriate temperature into a fuel cell FC can gain more advantage.

[0064] Then making a decision whether a process is completed or not in the step 6, when a process is not completed, each process is continued by returning to the step S2. And when a process is completed, it is the case such as stopping a drive of the cooling system for fuel cell M.

[0065] Besides, the present invention described above is not restricted to said embodiment but this can be available for a wide range of embodiment.

[0066] For example, it can be structured that a cooler to decrease the temperature of first cooling liquid is provided on the first supply line. What is more, although it is structured that the supply controller is comprised of the first solenoid valve and the second solenoid valve .etc, for example,

[0067] It can be structured that a flow rate can be varied through a butterfly valve driven by a stepping motor. It can be also structured that the supply controller is comprised of cross valve, etc. What is more, it can be also structured that the second cooling system is not provided since the heat exchanger has function of a radiator.

[0068] According to a cooling system for a fuel cell described in claim 1 of the aforementioned present invention, when the temperature of cooling liquid is within the adjustable range of temperature (usual) by a temperature-adjuster, cold cooling liquid is supplied into an ion exchanger. On the other hand, when the temperature of cooling liquid exceeded the adjustable range of temperature (high temperature) by a temperature-adjuster, cold cooling liquid supplying into a temperature-adjuster is increased.

[0069] Due to this, the temperature of cooling liquid can be smoothly adjusted, in addition, a lot of cooling liquid with low temperature as far as it is possible can be supplied into an ion exchanger, consequently, a fuel cell can be driven under the favorite condition.

[0070] Furthermore, according to a cooling system for fuel cell described in claim 2, a temperature-adjustment of cooling liquid supplying into a fuel cell can be more smoothly carried out by detecting the temperature of cooling liquid. 

What is claimed is:
 1. A cooling system for fuel cell comprising a heat exchanger to chill cooling liquid discharged from a fuel cell, a temperature-adjuster to adjust the temperature of cooling liquid supplying into said fuel cell after mixing cooling liquid chilled in said heat exchanger with cooling liquid bypassed said heat exchanger, an ion exchanger using an ion exchange resin to remove ion in said cooling liquid, a supply controller to supply cooling liquid bypassed said heat exchanger into said ion exchanger when the temperature of cooling liquid exceeds the adjustable range of temperature by said temperature-adjuster and to supply cooling liquid chilled in said heat exchanger into said ion exchanger when the temperature of cooling liquid is within the adjustable range of temperature by said temperature-adjuster.
 2. A cooling system for fuel cell described in claim 1 which further comprises a temperature-detector to detect the temperature of said cooling liquid, a said supply controller supplying cooling liquid bypassed said heat exchanger into said ion exchanger when the temperature of said cooling liquid is below the predetermined temperature, and supplying cooling liquid chilled in said heat exchanger into said ion exchanger when the temperature of said cooling liquid is above the predetermined value. 